Fecal Fermentation in Irritable Bowel Syndrome: Influence of Dietary Restriction of Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols

Digestion. 2016;94(1):50-6. doi: 10.1159/000448280. Epub 2016 Aug 4.


Background/aims: Dietary restriction of fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs) may relieve symptoms in patients with irritable bowel syndrome (IBS). We investigated whether this diet alters microbial fermentation, a process that may be involved in IBS symptom generation.

Methods: Patients with IBS were included consecutively to participate in a 4-week FODMAP restricted diet. IBS symptoms were evaluated by using the IBS severity scoring system (IBS-SSS). Short-chain fatty acids (SCFAs) were analyzed in fecal samples before and after the dietary intervention, both at baseline and after in vitro fermentation for 24 h.

Results: Sixty-three patients completed the study. Following the dietary intervention, IBS-SSS scores improved significantly (p < 0.0001). Total SCFA levels were reduced in fecal samples analyzed both at baseline (p = 0.005) and after in vitro fermentation for 24 h (p = 0.013). Following diet, baseline levels of acetic (p = 0.003) and n-butyric acids (p = 0.009) decreased, whereas 24 h levels of i-butyric (p = 0.003) and i-valeric acids (p = 0.003) increased. Fecal SCFA levels and IBS symptom scores were not correlated.

Conclusion: Dietary FODMAP restriction markedly modulated fecal fermentation in patients with IBS. Saccharolytic fermentation decreased, while proteolytic fermentation increased, apparently independent of symptoms.

Publication types

  • Clinical Trial

MeSH terms

  • Adult
  • Aged
  • Breath Tests
  • Colonoscopy
  • Diet, Carbohydrate-Restricted*
  • Disaccharides / metabolism
  • Fatty Acids, Volatile / analysis*
  • Fatty Acids, Volatile / metabolism
  • Feces / chemistry*
  • Female
  • Fermentation*
  • Gastrointestinal Microbiome*
  • Humans
  • Irritable Bowel Syndrome / diet therapy*
  • Irritable Bowel Syndrome / microbiology
  • Male
  • Middle Aged
  • Monosaccharides / metabolism
  • Norway
  • Oligosaccharides / metabolism
  • Polymers / metabolism
  • Severity of Illness Index
  • Young Adult


  • Disaccharides
  • Fatty Acids, Volatile
  • Monosaccharides
  • Oligosaccharides
  • Polymers
  • polyol